# Speed bump question - newton's laws

#### feveroffate

1.
You're driving down the road at 8 m/s and go over a speed bump. When you go over the bump, you feel lifted from your seat. Explain why.

I assumed it was because of inertia, but I'm not sure.

You weigh 700 N. If it is approximated that the speed bump is shaped like an arc of a circle, with radius of 10 m, find the magnitude of force the seats exerts on you as you go over the speed bump.

If F = mv^2/r, then would you just plug everything in directly?

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#### Delphi51

Homework Helper
The seat normally pushes upward on you with 700 N (because you push down on it with 700 N weight). While in circular motion, though, you experience a centrifugal force upward that reduces the 700 N.

#### feveroffate

So while in circular motion, you aren't pushing down on the seat with 700 N so you are lifted up?

#### Delphi51

Homework Helper
It is unlikely you will float up off the seat - that would take a terrific speed - but the force pressing you against the springs of the seat will be reduced so the spring compression will be less and you will go up a little bit.

#### feveroffate

But would the seat still exert 700 N upward? I mean, would I just plug in the numbers into the equation for the second part?

Homework Helper
700 - mv^2/r

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